48 INAUGURAL ADDRESS. 



recorded by Jukes in 1850— "The prevailing south-easterly dip 

 would put the clay slates under the gneiss, mica, and chlorite 

 slates," and independently observed by Selwyn in li<60. The 

 non-accejDtance of this view by the Government Geologist of South 

 Australia has compelled him to reverse the order of succession, and he 

 classes the lower series as "• Silurian (and Devonian), metamorphic 

 in jjart," and relegates the upper to " Palseozoic or Azoic, highly 

 metamorphic." ^' 



The elevated portions of the wide extending folds of the 

 Archseans have produced our mountain topography, and have sup- 

 plied the principal material of the newer deposits, all of them 

 terrigenous, Avliich fill the troughs of their plications and conceal 

 the continuity of far distant axes of elevation. Our now I'uined 

 Mount Lofty chain must have formed a lofty watershed in Lower 

 Palaeozoic times. The first of the deposits are the Cambrian, 

 which are much more broken and plicated than the underlying and 

 embracing Archa^ans, probably as the result of the continuation 

 of the earth movements after their deposition. These were then 

 compressed by the contractions of width in the synclinal folds. 

 The whole area of Australia seems to have been in a state of com- 

 parative quiescence since the period of those earth movements 

 which resulted in the plication of the Archseans, and in the 

 crumpling of the Lower Palaeozoics. Since then it seems to have 

 vmdergone oscillation of level within very narrow limits, and the 

 depressions which have taken place never brought more than the 

 margins of insular areas beneath the level of the sea. 



Victorian Palaeozoic physical geology in its broadest features is 

 represented by Mr. Selwyn f as consisting of a great crumpled, 

 contorted, and broken synclinal trough of Silurian and older strata, 

 overlain unconformably by an equally extensive broken and 

 undulating anticlinal arch of Upper Palaeozoic rocks. 



CAMBRIAN. 

 faj South Austrnlia, 

 1879. Tate (Trans. Hoy. Soc. S. Aust., vol. ii.,pp. xlviii. and 77) 

 refers the fossils collected by Mr. Tepper, at Ardrossan, Yorke 

 Peninsula, to Lower Silurian, employing the term in the Murchi- 

 sonian sense, though the Menevian series is implied. More 

 detailed evidences of a Cambrian fauna at that and other localities 

 are supplied by — 



1884. Woodward, H., Geol. Mag., p. 343. 



• Geological Map oi S. Aust., 1884. + Intercolonial Exhibition Essays, 1867, p. 153. 



